1. Field of the Invention
The present invention relates to a recording and reproducing apparatus, and more particularly to a recording and reproducing apparatus for recording and reproducing an audio mode information signal corresponding to an audio mode of a multi-channel audio signal in a high grade television broadcast.
2. Related Background Art
A VTR (video tape recorder) has been known as a recording and reproducing apparatus which can record a dual national language broadcast and a stereo-broadcast, but in this apparatus, when the dual national language broadcast is to be recorded and reproduced, only a main sound or a sub-sound is selected by a sound selection switch to prevent the mixture of the main sound and the sub-sound.
The number of sound channels is two or three.
A VTR used in a broadcasting station has been known as a VTR having a large number of sound channels and the number of sound channels is four to eight, but it is not compatible to the sound mode information of sound channels such as the dual national language or multi-national language broadcast and the stereo broadcast.
On the other hand, in a hi-vision broadcast (MUSE) of Japan, four channels of sound signals in an A-mode and two channels in a B-mode are transmitted and the various modes shown in Table 1 are available.
TABLE 1 Sound Mode Control Signals and Sound Modes Sound Mode Sound Mode (No. of Channels) Control Sound Channel Used Code Bits TV Sound Added Indep. Sound (--; No sound signal) 1 2 3 4 5 6 Mode Ste Mono Ste Mono CH 1 CH 2 CH 3 CH 4 * 0 0 0 0 0 0 A 1 1 L R L.sub.H R.sub.H 0 0 0 0 1 0 A 1 2 L R Main.sub.H Sub.sub.H 0 0 0 1 0 0 A 1 1 L R Main.sub.H -- * 0 0 0 1 1 0 A 1 L R -- -- * 0 0 1 0 0 0 A 2 1 Main Sub L.sub.H R.sub.H 0 0 1 0 1 0 A 2 2 Main Sub Main.sub.H Sub.sub.H * 0 0 1 1 0 0 A 2 1 Main Sub Main.sub.H -- 0 0 1 1 1 0 A 2 Main Sub -- -- * 0 1 0 0 0 0 A 1 1 Main -- L.sub.H R.sub.H 0 1 0 0 1 0 A 1 2 Main -- Main.sub.H Sub.sub.H 0 1 0 1 0 0 A 1 1 Main -- Main.sub.H -- * 0 1 0 1 1 0 A 1 Main -- -- -- * 0 1 1 0 0 0 A 1 -- -- L.sub.H R.sub.H 0 1 1 0 1 0 A 2 -- -- Main.sub.H Sub.sub.H 0 1 1 1 0 0 A 1 -- -- Main.sub.H -- 0 1 1 1 1 0 A -- -- -- -- * 0 0 0 0 0 1 A L.sub.MA R.sub.MA L.sub.SU R.sub.SU 0 0 0 0 1 1 A 1 2 L.sub.MA R.sub.MA Sub.sup.l Sub.sup.2 0 0 0 1 0 1 A 1 1 L.sub.MA R.sub.MA Sub -- 0 0 1 0 1 1 A 4 Main Sub.sup.1 Sub.sup.2 Sub.sup.3 0 0 1 1 0 1 A 3 Main Sub.sub.l Sub.sub.2 -- * 0 1 1 0 0 1 A 4 CH ster (3-1 system) L R C S 0 1 1 0 1 1 A 3 CH ster mono 1 chann L R C Sub 0 1 1 1 0 1 A 3 CH ster L R C -- 0 1 1 1 1 1 A 4 CR ster (2--2 system) L.sub.SU R.sub.SU L.sub.SU R.sub.SU * 1 0 0 1 1 0 B 1 L R * 1 0 1 1 1 0 B 2 Main Sub * 1 1 0 1 1 0 B 1 Main -- 1 1 1 1 1 0 B -- -- *Sound mode to be used for the time being Suffix H indicates added independent sound signal
In order to identify various modes, six sound mode control signal bits are allocated as shown in Table 1. As shown in FIG. 9, the sound mode control signal is transmitted as a part of control codes (22 bits) together with the sound signals of the respective channels as a MUSE bit stream in a MUSE signal.
In a receiving station, an audio signal of each channel is decoded (as a pre-selection audio signal) from the MUSE bit stream by an audio decoder, and a channel-selected or channel-exchanged audio signal (a post selection audio signal) is outputted in accordance with a content of an audio mode control signal decoded by the audio decoder or the selection operation by an audience.
For example, assuming that an A-mode 4-channel 3-1 system 4-channel stereo signal is transmitted via CH 1 for L (left), CH 2 for R (right), CH 3 for C (center) and CH 4 for S (surround), the L, R, C and S are selected if an audio reproducing system is a 4-channel system, and if it is a 2-channel system, EQU L.sub.1 =L+0.7C+j0.7S EQU R.sub.1 =R+0.7C+j0.7S
are selected by a matrix conversion. Those are post selection audio signals.
When a video signal containing the audio signal and the audio mode control signal is recorded in a VTR and reproduced therefrom, since a user selection condition is not uniquely determined, it is desirable that the VTR records the pre-selection audio signal and the audio mode control signal as they are and in the reproduction mode, it outputs the post selection audio signal in accordance with the user condition (the number of channels of the audio reproducing system and a language).
Since the prior art recording and reproducing apparatus is constructed as described above, when a tape having a two-language broadcast recorded thereon is to be reproduced, it is necessary to select a desired one of the languages by an audio selection switch, and when the audio channels are more than two, it is necessary to check the audio modes and the contents of the respective audio channels because the audio mode information does not correspond to the audio channels such as two-language or multi-language broadcast and the stereo braodcast. This is troublesome.
When a so-called after-recording in which an audio signal on a magnetic tape is recorded later is to be done, the audio mode may be changed by the after-recording if the number of channels is large. A VTR which solves the above problem and yet allows the recording and reproduction of the audio mode control signal has not been available.